termiox(7I)							  Ioctl Requests						       termiox(7I)

NAME

       termiox - extended general terminal interface

DESCRIPTION

       The  extended  general terminal interface supplements the termio(7I) general terminal interface by adding support for asynchronous hardware
       flow control, isochronous flow control and clock modes, and local implementations of additional asynchronous features. Some systems may not
       support all of these capabilities because of either hardware or software limitations.  Other systems may not permit certain functions to be
       disabled.  In these cases the appropriate bits will be ignored.	See <sys/termiox.h> for your system to find  out  which  capabilities  are
       supported.

   Hardware Flow Control Modes
       Hardware  flow  control	supplements  the  termio(7I) IXON, IXOFF, and IXANY character flow control. Character flow control occurs when one
       device controls the data transfer of another device by the insertion of control characters in the data stream  between  devices.   Hardware
       flow  control  occurs  when one device controls the data transfer of another device using electrical control signals on wires (circuits) of
       the asynchronous interface. Isochronous hardware flow control occurs when one device controls  the  data  transfer  of  another	device	by
       asserting  or  removing	the transmit clock signals of that device.  Character flow control and hardware flow control may be simultaneously
       set.

       In asynchronous, full duplex applications, the use of the Electronic Industries Association's EIA-232-D Request To Send (RTS) and Clear	To
       Send  (CTS) circuits is the  preferred method of hardware flow control.	An interface to other hardware flow control methods is included to
       provide a standard interface to these existing methods.

       The EIA-232-D standard specified only unidirectional hardware flow control - the Data Circuit-terminating Equipment or Data  Communications
       Equipment  (DCE)  indicates  to	the Data Terminal Equipment (DTE) to stop transmitting data.   The termiox interface allows both unidirec-
       tional and bidirectional hardware flow control; when bidirectional flow control is enabled, either the DCE or  DTE  can	indicate  to  each
       other  to stop transmitting data across the interface.  Note: It is assumed that the asynchronous port is configured as a DTE.  If the con-
       nected device is also a DTE and not a DCE, then DTE to DTE (for example, terminal or printer connected to computer) hardware  flow  control
       is possible by using a null modem to interconnect the appropriate data and control circuits.

   Clock Modes
       Isochronous  communication  is  a  variation  of  asynchronous  communication whereby two communicating devices may provide transmit and/or
       receive clock signals to one another. Incoming clock signals can be taken from the baud rate generator on the local isochronous	port  con-
       troller,  from  CCITT V.24 circuit 114, Transmitter Signal Element Timing - DCE source (EIA-232-D pin 15), or  from CCITT V.24 circuit 115,
       Receiver Signal Element Timing - DCE source  (EIA-232-D pin 17). Outgoing clock signals can be sent on CCITT V.24 circuit 113,  Transmitter
       Signal  Element	Timing	-  DTE	source	(EIA-232-D   pin  24),	on CCITT V.24 circuit 128, Receiver Signal Element Timing - DTE source (no
       EIA-232-D pin), or not sent at all.

       In terms of clock modes, traditional asynchronous communication is implemented simply by using the local baud rate generator as the  incom-
       ing transmit and receive clock source and not outputting any clock signals.

   Terminal Parameters
       The  parameters	that control the behavior of devices providing the termiox interface are specified by the termiox structure defined in the
       <sys/termiox.h> header.	Several ioctl(2) system calls that fetch or change these parameters use this structure:

	 #define   NFF	5
	 struct termiox {
	      unsigned short x_hflag;	    /* hardware flow control modes */
	      unsigned short x_cflag;	    /* clock modes */
	      unsigned short x_rflag[NFF];  /* reserved modes */
	      unsigned short x_sflag;	    /* spare local modes */
	 };

       The x_hflag field describes hardware flow control modes:

       RTSXOFF	       0000001	    Enable RTS hardware flow control
				    on input.
       CTSXON	       0000002	    Enable CTS hardware flow control
				    on output.
       DTRXOFF	       0000004	    Enable DTR hardware flow control
				    on input.
       CDXON	       0000010	    Enable  CD hardware flow control
				    on output.
       ISXOFF	       0000020	    Enable isochronous hardware flow
				    control on input

       The  EIA-232-D DTR and CD circuits are used to establish a connection between two systems. The RTS circuit is also used to establish a con-
       nection with a modem. Thus, both DTR and RTS are activated when an asynchronous port is opened. If DTR is used for hardware  flow  control,
       then  RTS must be used for connectivity. If CD is used for hardware flow control, then CTS must be used for connectivity. Thus, RTS and DTR
       (or CTS and CD) cannot both be used for hardware flow control at the same time. Other mutual exclusions may apply, such as the simultaneous
       setting of the termio(7I) HUPCL and the	termiox DTRXOFF bits, which use the DTE ready line for different functions.

       Variations  of  different  hardware  flow  control  methods may be selected by setting the the appropriate bits. For example, bidirectional
       RTS/CTS flow control is selected by setting both the RTSXOFF and CTSXON bits and bidirectional DTR/CTS flow control is selected by  setting
       both the DTRXOFF and CTSXON. Modem control or unidirectional CTS hardware flow control is selected by setting only the CTSXON bit.

       As  previously  mentioned, it is assumed that the local asynchronous port (for example, computer) is configured as a DTE.  If the connected
       device (for example,  printer) is also a DTE, it is assumed that the device is connected to the computer's asynchronous port using  a  null
       modem  that swaps control circuits (typically RTS and CTS).  The connected DTE drives RTS and the null modem swaps RTS  and CTS so that the
       remote RTS is received as CTS by the local DTE.	In the case that CTSXON is set for hardware flow control, printer's lowering  of  its  RTS
       would cause CTS seen by the computer to be lowered.  Output to the printer is suspended until the printer's raising of its RTS, which would
       cause CTS seen by the computer to be raised.

       If RTSXOFF is set, the Request To Send (RTS) circuit (line) will be raised, and if the asynchronous port needs to have its  input  stopped,
       it  will  lower	the  Request  To Send (RTS) line. If the RTS line is lowered, it is assumed that the connected device will stop its output
       until RTS is raised.

       If CTSXON is set, output will occur only if the Clear To Send (CTS) circuit (line) is raised by the connected device. If the  CTS  line	is
       lowered by the connected device, output is suspended until CTS is raised.

       If DTRXOFF is set, the DTE Ready (DTR) circuit (line) will be raised, and if the asynchronous port needs to have its input stopped, it will
       lower the DTE Ready (DTR) line. If the DTR line is lowered, it is assumed that the connected device will  stop  its  output  until  DTR	is
       raised.

       If  CDXON is set, output will occur only if the Received Line Signal Detector (CD) circuit (line) is raised by the connected device. If the
       CD line is lowered by the connected device, output is suspended until CD is raised.

       If ISXOFF is set, and if the isochronous port needs to have its input stopped, it will stop the outgoing clock signal. It is  assumed  that
       the  connected  device  is using this clock signal to create its output. Transit and receive clock sources are programmed using the x_cflag
       fields. If the port is not programmed for external clock generation, ISXOFF is ignored.	Output isochronous flow control  is  supported	by
       appropriate clock source programming using the x_cflag field and enabled at the remote connected device.

       The x_cflag field specifies the system treatment of clock modes.

       XMTCLK		 0000007     Transmit clock source:
       XCIBRG		 0000000     Get  transmit clock from inter-
				     nal baud rate generator.

       XCTSET		 0000001     Get transmit clock from  trans-
				     mitter  signal  element  timing
				     (DCE source) lead,  CCITT	V.24
				     circuit 114, EIA-232-D pin 15.
       XCRSET		 0000002     Get    transmit	clock	from
				     receiver signal element  timing
				     (DCE  source)  lead, CCITT V.24
				     circuit 115, EIA-232-D pin 17.
       RCVCLK		 0000070     Receive clock source:
       RCIBRG		 0000000     Get receive clock from internal
				     baud rate generator.
       RCTSET		 0000010     Get  receive  clock from trans-
				     mitter  signal  element  timing
				     (DCE  source)  lead, CCITT V.24
				     circuit 114, EIA-232-D pin 15.
       RCRSET		 0000020     Get receive clock from receiver
				     signal   element	timing	(DCE
				     source) lead, CCITT  V.24	cir-
				     cuit 115, EIA-232-D pin 17.
       TSETCLK		 0000700     Transmitter signal element tim-
				     ing (DTE  source)	lead,  CCITT
				     V.24 circuit 113, EIA-232-D pin
				     24, clock source:
       TSETCOFF 	 0000000     TSET clock not provided.
       TSETCRBRG	 0000100     Output receive baud rate gener-
				     ator on circuit 113.
       TSETCTBRG	 0000200     Output  transmit baud rate gen-
				     erator on circuit 113
       TSETCTSET	 0000300     Output transmitter signal	ele-
				     ment  timing  (DCE  source)  on
				     circuit 113.
       TSETCRSET	 0000400     Output receiver signal  element
				     timing  (DCE source) on circuit
				     113.
       RSETCLK		 0007000     Receiver signal element  timing
				     (DTE  source)  lead, CCITT V.24
				     circuit 128, no EIA-232-D	pin,
				     clock source:
       RSETCOFF 	 0000000     RSET clock not provided.
       RSETCRBRG	 0001000     Output receive baud rate gener-
				     ator on circuit 128.
       RSETCTBRG	 0002000     Output transmit baud rate	gen-
				     erator on circuit 128.
       RSETCTSET	 0003000     Output  transmitter signal ele-
				     ment  timing  (DCE  source)  on
				     circuit 128.
       RSETCRSET	 0004000     Output  receiver signal element
				     timing (DCE) on circuit 128.

       If the XMTCLK field has a value of XCIBRG the transmit clock is taken from the hardware internal baud rate generator, as  in  normal  asyn-
       chronous  transmission.	If XMTCLK = XCTSET the transmit clock is taken from the Transmitter Signal Element Timing (DCE source) circuit. If
       XMTCLK = XCRSET the transmit clock is taken from the Receiver Signal Element Timing (DCE source) circuit.

       If the RCVCLK field has a value of RCIBRG the receive clock is taken from the hardware Internal Baud Rate Generator, as in normal asynchro-
       nous transmission. If RCVCLK = RCTSET the receive clock is taken from the Transmitter Signal Element Timing (DCE source) circuit. If RCVCLK
       = RCRSET the receive clock is taken from the Receiver Signal Element Timing (DCE source) circuit.

       If the TSETCLK field has a value of TSETCOFF the Transmitter Signal Element Timing (DTE source) circuit is not driven. If TSETCLK = TSETCR-
       BRG  the  Transmitter  Signal  Element Timing (DTE source) circuit is driven by the Receive Baud Rate Generator. If TSETCLK = TSETCTBRG the
       Transmitter Signal Element Timing (DTE source) circuit is driven by the Transmit Baud Rate Generator. If TSETCLK = TSETCTSET the  Transmit-
       ter  Signal Element Timing (DTE source) circuit is driven by the Transmitter Signal Element Timing (DCE source). If TSETCLK = TSETCRBRG the
       Transmitter Signal Element Timing (DTE source) circuit is driven by the Receiver Signal Element Timing (DCE source).

       If the RSETCLK field has a value of RSETCOFF the Receiver Signal Element Timing (DTE source) circuit is not driven. If RSETCLK =  RSETCRBRG
       the  Receiver Signal Element Timing (DTE source) circuit is driven by the Receive Baud Rate Generator.  If RSETCLK = RSETCTBRG the Receiver
       Signal Element Timing (DTE source) circuit is driven by the Transmit Baud Rate Generator. If RSETCLK = RSETCTSET the Receiver  Signal  Ele-
       ment  Timing (DTE source) circuit is driven by the Transmitter Signal Element Timing (DCE source). If RSETCLK = RSETCRBRG the Receiver Sig-
       nal Element Timing (DTE source) circuit is driven by the Receiver Signal Element Timing (DCE source).

       The x_rflag is reserved for future interface definitions and should not be used by any implementations. The x_sflag may be  used  by  local
       implementations wishing to customize their terminal interface using the	termiox ioctl system calls.

IOCTLS

       The  ioctl(2) system calls have the form:

	 ioctl (fildes, command, arg) struct termiox * arg;

       The commands using this form are:

       TCGETX	  The argument is a pointer to a termiox structure. The current terminal parameters are fetched and stored into that structure.

       TCSETX	  The argument is a pointer to a termiox structure.  The current terminal parameters are set from the values stored in that struc-
		  ture.  The change is immediate.

       TCSETXW	  The argument is a pointer to a termiox structure.  The current terminal parameters are set from the values stored in that struc-
		  ture.   The  change  occurs after all characters queued for output have been transmitted. This form should be used when changing
		  parameters that will affect output.

       TCSETXF	  The argument is a pointer to a termiox structure.  The current terminal parameters are set from the values stored in that struc-
		  ture.   The change occurs after all characters queued for output have been transmitted; all characters queued for input are dis-
		  carded and then the change occurs.

FILES

       /dev/*

SEE ALSO

       stty(1), ioctl(2), termio(7I)

NOTES

       The  termiox(7I) system call is provided for compatibility with previous releases and  its use is discouraged.	Instead,  the	termio(7I)
       system call is recommended.  See termio(7I) for usage information.

SunOS 5.11							    3 Jul 1990							       termiox(7I)